Quantitative Relationship Between Consumption and Excretion of Dry Matter by Larvae of the Pale Western Cutworm, Agrotis orthogonia Morr. (Lepidoptera: Noctuidae)

Abstract

The quantities of excreta produced by aphids (Auclair, 1957) and locusts (Dadd, 1960) have been used to estimate the relative consumption of different food materials. Likewise the quantities of food consumed by some other insects have been conveniently estimated by counting fecal pellets (Thorsteinson, 1953; Ito, 1960). Ito (1960) stated without supporting data “there is a highly significant correlation between the amount of mulberry leaves ingested and numbers of feces produced”. Nevertheless there appear to be no published quantitative measurements made on individual insects that show the relationship between the quantities of food consumed and excreta passed. This note gives the relationship between the quantities of dry matter (D. M.) consumed and excreted for three larval instars of the pale western cutworm, Agrotis orthogonia Morr., fed two varieties of etiolated wheat sprouts, Thatcher (Triticum aestivum L. emend Thell.) and Golden Ball (T. durum Desf.). In addition the relationship between D. M. consumed and numbers of fecal pellets produced or D. M. excreted by fifth-instar larvae were determined for two diets that differed considerably in nutritional value.